Low-Intensity Focused Ultrasound for Treatment-Resistant Depression

Inclusion criteria: * Male or female * Age 18-70 * Normal or corrected-to normal vision and hearing * Primary diagnosis of major depressive disorder, moderate/severe per DSM-5 (MADRS \>20) * The duration of the illness must exceed one year * Must be medically stable as determined by investigator * Patient must have attempted and failed treatment with at least 2 SSRI and 1 augmentation * History of rTMS is permitted, but not required Exclusionary criteria: * Diagnosis of primary DSM-5 depressive disorder other than MDD * Anxiety disorders such as GAD are permitted as long as MDD is primary * Diagnosis of schizophrenia or bipolar disorder * Current use of any non-prescribed psychoactive medications or drugs (aside from medications for treatment of MDD) * Contraindication to enter the MRI environment. * Pregnancy (or suspected/possible pregnancy or plan to become pregnant in the short term). * Urine Pregnancy Test: If the subject is a woman of childbearing potential and /or a man capable of fathering a child before, during, and/or after participation precaution should be taken. Examples of acceptable methods of birth control for participants involved in the study includes: birth control pills, patch, IUD, condom, sponge, diaphragm with spermicide, or avoiding sexual activity that could cause the subject to become pregnant. * Inability to adhere to treatment schedule. * Initiation of new antidepressant treatment at the time of study randomization.